Alpina Watch Seastrong Diver 300 Mens AL-520BY4H6. Our customers benefit from continuous technical advances that match the ever increasing demands of modern sport challenges. Our manufacture is both workshop and hi tech lab, and Alpina continually invests in state of the art machinery and processes. Our watch makers use the most modern, high precision tools available in the world today, and every watch undergoes strict quality control tests and inspection before leaving our factory.